our perception of the environment, our values as a nation have changed. and that's why we can look at friant dam today and say, maybe we never should have done that. but in the context of the '30s it was >> reporter: for now, it remains impossible for salmon to swim the length of the river and spawn. but a few fish are living in the river, and are reproducing. still, it may take another 20 years before the restoration of the san joaquin can be judged a success or a failure. >> suarez: you can see historical images of life and development in the san joaquin river valley dating back to the 1800s. find that slide show on our homepage. >> woodruff: and to the analysis of shields and brooks: syndicated columnist mark shields, and "new york times" columnist david brooks. welcome back, gentlemen. so let's start by talking about immigration. the senate passed its bill w what two weeks ago, mark, i think 14 republicans voted for it. but now that it's in the house, the republicans are balking, what is going on if. >> well, it's a different institution, judy. the re